The present disclosure relates generally to subterranean formation operations and, more particularly, to scale remediation in a subterranean formation wellbore above a downhole safety valve.
Downhole safety valves (DSV) are installed in wellbores (which may be used interchangeably with simply “well” herein) to isolate wellbore pressure and fluids in the event of an emergency or catastrophic failure of wellbore equipment (e.g., downhole or surface equipment). The DSV thus functions as a failsafe to prevent the uncontrolled release of fluids from a wellbore, including fluids originating from the wellbore and those introduced there (e.g., treatment fluids). Certain local governments require a DSV, or require the failsafe mechanisms to prevent the uncontrolled release of fluids from a wellbore (which a DSV is designed to achieve). For example, regulations for wellbores in the North Sea require a DSV and if the functionality of the DSV is lost, the wellbore must be taken off of production. The DSV is typically installed as part of a completion design and is tubing retrievable, such as in the event of a malfunction of the DSV. Accordingly, the DSV can be retrieved to the surface and its function resolved during a workover (including replacement of the DSV entirely), which is often costly in terms of time and monetary price.
Throughout the production of a wellbore, scale can build up on the inner surfaces of completion equipment, including the DSV and surrounding area, as well as wellbore surfaces. Scale is a deposit or coating formed on the surface of a metal, rock, or other material. The buildup of scale on and around a DSV can render the DSV either more difficult to operate or completely inoperable. For example, the DSV can be scaled such that the flapper valve is unable to fully close in the event of an emergency, or the area surrounding the DSV can be scaled such that the operability (e.g., opening or closing) of the DSV is compromised. Accordingly, if scale is not inhibited or removed during the lifetime of a wellbore from a DSV (which buildup has occurred), the functionality of the DSV is compromised and a costly workover may be required.